Centrifugal fan

ABSTRACT

A centrifugal fan according to an exemplary embodiment of the present invention includes: a hub penetrated by a rotational axis; a plurality of main blades extended in a radial direction from a predetermined point of the top of the hub; a bell mouth formed on a top of the exteriors of the plurality of main blades; and a plurality of auxiliary blades extended in the radial direction between the plurality of main blades, wherein a ratio (D1/D2) of an inner diameter D1 to an outer diameter D1 of each of the auxiliary blades is in the range of 07 to 0.9.

CROSS REFERENCES RELATED APPLICATIONS

The present application claims the benefits of priority to Korean PatentApplication No. 10-2010-0072163 (filed on Jul. 27, 2010), which isherein incorporated by reference in its entirety.

THE BACKGROUND

1. The Field

The present invention relates to a centrifugal fan.

2. Description of the Related Art

A centrifugal fan suctions air in an axial direction and discharges theair in a radial direction. The centrifugal fan may be mounted on anevaporation chamber or a machine chamber of an air conditioner and arefrigerator. In particular, in the case of the refrigerator, an area ofa cooled air passage is decreased in order to increase a volume in therefrigerator, such that a passage resistance is increased. In order tosolve the problem, a centrifugal fan having a high constant pressureproperty is generally used.

However, a general centrifugal fan in the related art has disadvantagesto be described below.

Specifically, while the axial-direction flow is switched to theradial-direction flow, air is discharged from a trailing edge of a fanblade at an angle between the axial direction and the radial direction.Therefore, a larger flow rate is generated from a lower side than anupper side of the trailing edge of the fan blade.

Accordingly, a large pressure difference between the upper side and thelower side of the trailing edge is caused, and as a result, some of theair discharged through the trailing edge flows backward through a bellmouth mounted on the top of the blade. Therefore, the flow is lost andnoise increases and an eddy phenomenon occurs at the upper side of thetrailing edge, such that fan efficiency deteriorates.

THE SUMMARY

The present invention has been made in an effort to solve the problems.

An exemplary embodiment of the present invention provides a centrifugalfan including: a hub penetrated by a rotational axis; a plurality ofmain blades extended in a radial direction from a predetermined point ofthe top of the hub; a bell mouth formed on a top of the exteriors of theplurality of main blades; and a plurality of auxiliary blades extendedin the radial direction between the plurality of main blades, wherein aratio (D1/D2) of an inner diameter D1 to an outer diameter D1 of each ofthe auxiliary blades is in the range of 07 to 0.9.

The following effects can be achieved by the centrifugal fan accordingto the exemplary embodiment of the present invention configured asabove.

First, a constant pressure and a flow rate of a fan are increased byinstalling an auxiliary blade between main blades.

Second, since the flow rate increases at the same rpm, rpm can decreasewhile the same flow rate is maintained, and as a result, noise isreduced.

Third, a velocity distribution of a flow discharged through a trailingedge of the auxiliary blade is substantially uniform, such that apressure difference between an upper side and a lower side of thetrailing edge is minimized, and as a result, a flow property in whichthe discharged air flows backward is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a centrifugal fan according to anexemplary embodiment of the present invention.

FIG. 2 is a plan view of a centrifugal fan according to an exemplaryembodiment of the present invention.

FIG. 3 is a bottom view of a centrifugal fan according to an exemplaryembodiment of the present invention.

FIG. 4 is a side view of a centrifugal fan according to an exemplaryembodiment of the present invention.

FIG. 5 is a graph showing a comparison of a flow rate for each rpmbetween a centrifugal fan according to an exemplary embodiment of thepresent invention and a general centrifugal fan with no auxiliary blade.

FIG. 6 is a graph showing a comparison of noise for each frequencybetween a centrifugal fan according to an exemplary embodiment of thepresent invention and a general centrifugal fan with no auxiliary blade.

THE DETAILED DESCRIPTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration specific preferredembodiments in which the invention may be practiced. These embodimentsare described in sufficient detail to enable those skilled in the art topractice the invention, and it is understood that other embodiments maybe utilized and that logical structural, mechanical, electrical, andchemical changes may be made without departing from the spirit or scopeof the invention. To avoid detail not necessary to enable those skilledin the art to practice the invention, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined only by the appended claims.

Hereinafter, a centrifugal fan according to an exemplary embodiment ofthe present invention will be described in detail with reference to theaccompanying drawings.

FIG. 1 is a perspective view of a centrifugal fan according to anexemplary embodiment of the present invention, FIG. 2 is a plan view ofa centrifugal fan according to an exemplary embodiment of the presentinvention, and FIG. 3 is a bottom view of a centrifugal fan according toan exemplary embodiment of the present invention.

Referring to FIGS. 1 to 3, the centrifugal fan 10 according to theexemplary embodiment of the present invention includes a hub 11penetrated by a rotational axis and having a circular cone shape inwhich a diameter increases toward the bottom, a blade extended withbeing rounded in a radial direction at an edge of the hub, and a bellmouth 14 formed on the top of the blade.

Specifically, the blade includes main blades 12 extended from the edgeof the bottom of the hub and auxiliary blades 13 each of which the topis connected to the bottom of the bell mouth 14. The auxiliary blade 13is provided between the main blade 12 to improve flow loss caused by adifference in velocity and pressure between an upper side and a lowerside of a trailing edge of the blade.

The hub 11 has the circular cone shape in which the diameter increasestoward the bottom to serve to diffuse air suctioned in a rotationalaxial direction to a radial direction. In addition, the main blade 12extends in the radial direction starting from a point spaced aparttoward the center from the edge of the bottom of the hub 11 by apredetermined distance. In addition, the main blade 12 is extended withbeing rounded at a predetermined curvature. Further, the auxiliary blade13 is shorter than the main blade 12 and does not contact the hub 11.That is, the auxiliary blade 13 is connected to only the bell mouth 14.

Moreover, an outer diameter of the bell mouth 14 is larger than that ofthe bottom of the hub 11. In addition, the inner edge of the bell mouth14 is rounded in an extending direction of the rotational axis of thehub 11. In other words, the inner edge of the bell mouth 14 is extendedby a predetermined length with being rounded toward the top of the hub11.

Meanwhile, in the structure of the main blade 12, an end of the mainblade at the side of the hub 11 may be defined as a leading edge 121 andan opposite end to the leading edge 121 may be defined as a trailingedge 122. Of course, similarly, both ends of the auxiliary blade 13 mayalso be defined as a leading edge 131 and a trailing edge 132.

Specifically, when the centrifugal fan 10 is viewed from the top (FIG.2), a diameter D1 of a circumference linking the leading edges of theauxiliary blades 13 may be substantially equal to or larger than thediameter of the bottom of the hub 11. In addition, the trailing edges122 and 132 of the main blade 12 and the auxiliary blade 13 arepositioned on the same circumference and may be substantially equal tothe diameter D2 of the bell mouth 14. In other words, the diameter ofthe circumference passing the leading edges 131 of the auxiliary blades13 may be represented by D1 and the diameter of the circumferencepassing the trailing edges 132 may be represented by D2.

Further, the diameter D1 of the circumference passing the leading edges131 of the auxiliary blades 13 may be equal to or larger than an innerdiameter of the bell mouth 14. In addition, the auxiliary blade 13 maybe interposed between one or two or more main blades 12. Moreover,hereinafter, the diameter D1 of the circumference passing the leadingedges 131 of the auxiliary blade 13 is defined as an inner diameter ofthe auxiliary blade 13 and the diameter D2 of the circumference passingthe trailing edges 132 is defined as an outer diameter of the auxiliaryblade 13.

Meanwhile, the inner diameter D1 of the auxiliary blade 13 may be largerthan the diameter of the circumference linking the leading edges 121 ofthe main blade 12, i.e., an inner diameter of the main blade 12.

Further, a ratio (D1/D2) of the inner diameter to the outer diameter ofthe auxiliary blade 13 is preferably in the range of 0.7 to 0.9 and thisis a result extracted through tests performed at several times.

FIG. 4 is a side view of a centrifugal fan according to an exemplaryembodiment of the present invention.

Referring to FIG. 4, the auxiliary blade 13 is extended by apredetermined length toward the bottom of the hub 11 from the bottom ofthe bell mouth 14. Herein, a length from an upper end to a lower end ofthe trailing edge 132 of the auxiliary blade 13 is defined as a width W1of the trailing edge 132 of the auxiliary blade 13. In another aspect,the width W1 may be the height of the trailing edge 132 from the bottomof the bell mouth 14.

In addition, the main blade 12 is extended from a predetermined point ofthe top of the hub 11. Further, a length from an upper end to a lowerend of the trailing edge 122 of the main blade 12 is defined as a widthW2 of the trailing edge 122 of the auxiliary blade 12. In anotheraspect, the width W2 may be the height of the trailing edge 122 from thebottom of the bell mouth 14.

Further, a ratio (W1/W2) of the trailing edge 132 of the auxiliary blade13 to the width of the trailing edge 122 of the main blade 12 ispreferably in the range of 0.45 to 0.65 and this is also a resultextracted through tests performed at several times.

FIG. 5 is a graph showing a comparison of a flow rate for each rpmbetween a centrifugal fan according to an exemplary embodiment of thepresent invention and a general centrifugal fan with no auxiliary blade.

Referring to FIG. 5, a flow rate generated by the centrifugal fan 10according to the exemplary embodiment of the present invention is morethan that of the general centrifugal fan in the same rpm. Accordingly,when the same flow rate is generated, since the rpm of the centrifugalfan 10 of the exemplary embodiment of the present invention may be setto be less than that of the general centrifugal fan, power consumptioncan be reduced.

FIG. 6 is a graph showing a comparison of noise for each frequencybetween a centrifugal fan according to an exemplary embodiment of thepresent invention and a general centrifugal fan with no auxiliary blade.

Referring to FIG. 6, a sound pressure level (SPL) generated in thecentrifugal fan 10 according to the exemplary embodiment of the presentinvention is lower than that of the general centrifugal fan under thesame frequency.

This means that the magnitude of noise generated in the centrifugal fan10 is smaller than that of the general centrifugal fan at the same rpmor frequency. Accordingly, fan noise can be reduced by using thecentrifugal fan 10 according to the exemplary embodiment of the presentinvention.

1. A centrifugal fan, comprising: a hub penetrated by a rotational axis;a plurality of main blades extended in a radial direction from apredetermined point of the top of the hub; a bell mouth formed on a topof the exteriors of the plurality of main blades; and a plurality ofauxiliary blades extended in the radial direction between the pluralityof main blades, wherein a ratio (D1/D2) of an inner diameter Dl to anouter diameter D1 of each of the auxiliary blades is in the range of 07to 0.9.
 2. The centrifugal fan of claim 1, wherein the auxiliary bladeis extended on a bottom of the bell mouth and is spaced apart from thehub.
 3. The centrifugal fan of claim 2, wherein the width of theauxiliary blade is smaller than that of the main blade.
 4. Thecentrifugal fan of claim 2, wherein the length of the auxiliary blade islarger than that of the main blade.
 5. The centrifugal fan of claim 2,wherein one or plural main blades are positioned between the adjacentauxiliary blades.
 6. The centrifugal fan of claim 2, wherein a ratio(W1/W2) of the width w1 of the trailing edge of the auxiliary blade tothe width W2 of the trailing edge of the main blade is in the range of0.45 to 0.65.
 7. The centrifugal fan of claim 2, wherein the innerdiameter D1 of the auxiliary blade is equal to or larger than thediameter of the bottom of the hub.
 8. The centrifugal fan of claim 2,wherein the inner diameter D1 of the auxiliary blade is equal to orlarger than the inner diameter of the bell mouth.